This invention relates to tufting machines and more particularly to a cut/loop hook module having removable spring clips therein.
In a tufting machine a multiplicity of yarn carrying needles penetrate a backing material to insert loops of yarn therein which loops are seized and either thereafter shed by a looper to produce loop pile or are maintained on a hook and thereafter cut by a knife to produce cut pile. When loop and cut pile are to be produced in the same row of stitching a spring clip is secured to each cut pile hook and biased against the bill of the hook and the yarn fed to the needles is controlled so that on selective stitches less yarn is fed to a selective needle to backdraw yarn from a previous loop to cause that loop to force the spring clip away from the bill of the hook and be withdrawn from the hook to form an uncut loop. When sufficient yarn is fed to the needle, no yarn is backdrawn from the previous loop and the loop remains on the hook to be cut subsequently by a knife, as disclosed in Card U.S. Pat. No. 3,084,645.
As the gauge of tufted products have decreased, i.e., the spacing between adjacent rows of stitches and thus between respective needles and loopers or hooks, modules have been developed wherein the shanks of respective loopers or hooks are embedded in a common body in side-by-side disposition. Such constructions are illustrated in Bardsley U.S. Pat. Nos. 4,303,024 and 4,739,717. This modular construction substantially eliminates the difficulties of aligning hooks or loopers in a respective hook or looper bar of the tufting machine since the hooks or loopers are aligned in a jig during the formation of the module. Moreover, to produce cut/loop Bardsley U.S. Pat. No. 4,241,675 developed a module in which the hooks are mounted in a first body member and the clips are mounted in a second body member, the body members being adapted and arranged to locate the hooks and clips in the required cooperative relationship.
One difficulty with the modular construction is that of replacability of a broken gauge part, i.e., a hook, looper or clip. If a gauge part breaks the entire module must be removed and replaced, the module including the unbroken gauge parts generally being discarded or returned for re-manufacture. In cut/loop apparatus, the clip is particularly vulnerable to damage, and it is usually the case in practice that damage to a particular clip results also in damage to adjacent clips. Since the cost of a clip component is but a relatively small portion of the total cost of a hook/clip combination, the need to discard such a combination, or indeed a plurality thereof in the case of non-modular hook/clip combinations because of damage to or failure of a single clip represents a financial burden out of all proportion to the fault. In Slattery U.S. Pat. No. 4,522,132 the spring clip of a cut/loop hook may be removed and replaced from the hook rapidly by providing cooperating male and female fastening means for positioning and aligning and thus removably attaching the clip to the hook. Even in this situation, if a number of clips are damaged, the down-time required for removing and replacing a number of clips may be all out of proportion to the damage. Thus, modular construction is desirable.
In the utilization of hook/clip combinations to produce cut/loop fabric, yarn tension and component precision effect the quality of the goods produced. If improper and inconsistent tension of the clips against the hooks is present, the resultant product is reflective of this difficulty. Control of these factors becomes significantly more important as the gauge of the tufting machine is reduced. Moreover, the free movement of the parts and interference therebetween clearly creates difficulties when the spacing between adjacent clips and hooks is relatively close. Thus, it is highly desirable to use modules for mounting the hooks and clips in the proper relationship. For these reasons modular cut/loop hooks having the hooks and clips permanently secured within the modular body have been utilized. Only the aforesaid Bardsley U.S. Pat. No. 4,241,675 developed an arrangement wherein broken clips, albeit as a separate modular unit, may be removed from hook modules.